In the art of pedal-driven vehicles, the need has been long felt of saddle structures which, while still being comfortable and stiff, are as light as possible, to improve cycling performances.
As it is known, a saddle structure essentially comprises a rigid support body, generally known as “shell”, a padding laid thereon, and means for securing the assembly to the frame of the bicycle, typically including one or more specially shaped bars attached to the seat post by clamps.
The shell component is particularly stressed when riding the vehicle, and must therefore have high mechanical strength properties. Nevertheless, it must also be flexible, to maintain its comfort and be able to absorb the vibrations which are forcibly associated to riding.
Traditionally, shells were made of metal or wood, which caused them to have a heavy weight and poor flexibility.
Then, with the advent of polymers, shells began to be manufactured from polymer-based materials, which had a definitely lighter weight and a higher flexibility.
A drawback of such prior art shells is that, while polymers have a light weight, they are by their nature rather flexible and have a low bending and compressive strength.
In recent times, low density materials have been increasingly used in industry, namely carbon, glass, kevlar® fiber reinforced polymers or the like, or particle- or metal-nanoreinforced polymers, e.g. nanoreinforced with titanium, aluminum, magnesium.
To achieve an acceptable stiffness, these prior art structures are composed of various superimposed layers. This configuration is critical, because these materials are by their nature rather flexible and the superposition of multiple layers is the only arrangement that can afford a stiff and strong structure.
As it is known, the bending strength of a rigid body is a function of the moment of inertia, which is a maximum when the section areas are at the greatest distance from the neutral axis.
From European Patent EP-B1-1305209 by the applicant hereof, a saddle of the above type is known, which has a plurality of first superimposed layers, secured to one or more layers having a different conformation.
While this solution provides a stiff saddle having a rather lightweight construction, it still has a few apparent drawbacks.
First, the above mentioned materials have a rather high cost, and this results in an unavoidable increase in the final price of the product.
Furthermore, even when low density materials are used, the superposition of multiple layers somewhat increases the weight of the shell, thereby impairing cycling performances.